It is an enhanced version of hn_captcha package written originally by Nogajski. This version provides the following enhancements:

- Case-sensitive validation option
- Display an optional refresh link to generate a new picture with a different key using AJAX. Generating a new text this way does not count to the user attempts limit verification.
- Use of prefix for image file names
- Optional garbage collector to remove generated files after a given period
- Support for programmatic POST redirection to perform the CAPTCHA validation and then redirect the form data to any processing page
- Support for internationalization of messages
- Display the current CAPTCHA configuration
- Configurable passing an array of settings array when the object is initialized